Updated

Anti-government protesters in Thailand entered a military compound Thursday and disrupted a key meeting on the fate of controversial July elections, forcing the acting prime minister to flee for security reasons. That followed an overnight attack on protesters that left three dead and at least 22 injured, the latest spasm of violence in Thailand's political crisis.

Caretaker Prime Minister Niwattumrong Boonsongpaisan was meeting with the Election Commission at an air force academy outside Bangkok to discuss whether elections can be held July 20 or need to be delayed due to the political conflict. He had chosen the location for security reasons to avoid protesters in the capital who are opposed to the election and are calling for an unelected, appointed prime minister.

Despite the presence of riot police and other security, about 100 protesters who marched from central Bangkok entered the compound through a side entrance, blowing whistles and waving Thai flags. Niwattumrong and several Cabinet ministers at the meeting were alerted to the protesters' arrival and hastily ended the meeting, got into their cars and were driven away, officials said.

"The government called off the meeting for security reasons," the Election Commission's secretary-general Somchai Srisutthiyakorn told reporters. He said the government has suggested that future meetings be held by teleconference.

Thailand's political crisis deepened last week when the Constitutional Court removed Prime Minister Yingluck Shinawatra for nepotism along with nine Cabinet members in a case that many viewed as politically motivated. Protesters say Yingluck's removal is not enough, though. She was simply replaced by Niwattumrong, who was a deputy premier from the ruling party.

The protesters are pushing the Senate and the nation's courts to intervene in the crisis to install a "neutral" prime minister, but the government says that is a threat to the nation's democratic system and would be tantamount to a judicial coup.

Yingluck's party would most almost certainly win another election, and protesters are opposed to July elections without political reforms implemented first. They want to set up an unelected "people's council" to implement still-undefined changes to completely remove Yingluck's family influence from politics before any polls take place, which the current ruling party would likely win because of widespread support among the rural poor.

The pre-dawn attacks near Bangkok's Democracy Monument, where some protesters are camping out, marked the latest spasm of violence to hit the capital since protesters launced a campaign to oust the government six months ago.

Police Col. Krailert Buakaew said at least three grenades were detonated and machine-guns were fired at protesters in the small encampment. He said the dead included one sleeping protester and a volunteer guard. He said investigators are collecting evidence but have so far found only puddles of blood at the scene.

The Erawan Medical Center, which tracks casualties, said that the toll was three dead and at least 22 wounded.

The attack brings the nationwide toll since protests began last November to 28 dead and about 800 wounded.

Oyjai Suangchaiyaphum, a 55-year-old protester who was sleeping at the base of Democracy Monument, said that attackers fired at least two grenades and an automatic weapon toward their encampment. Oyjai was lightly wounded in the leg by shrapnel, but medics treated her at the spot.

Thailand's political crisis began in 2006, when Yingluck's brother, former Prime Minister Thaksin Shinawatra, was toppled by a military coup after being accused of corruption, abuse of power and disrespect for King Bhumibol Adulyadej.

Thaksin, a former telecommunications billionaire, remains highly popular among the poor in Thailand's north and northeast, and parties controlled by him have won every national election since 2001. The anti-government protesters, aligned with the opposition Democrat Party and backed by the country's traditional elites, say they want to remove all traces of his political machine from politics.